Which statement best defines a cell?

Which statement best defines a cell?

• A. The smallest unit capable of performing life functions.
• B. A molecule.
• C. A tissue.
• D. An organ.

Answer: (A)

A cell is the basic unit of life—the smallest entity that can carry out the processes essential for life. It can perform metabolism, respond to its environment, grow, and, in many cases, reproduce. In single-celled organisms, one cell does all the life functions. In multicellular organisms, cells specialize and work together, but each cell still carries out its own life processes. A molecule is just a chemical unit of matter and isn’t alive by itself. A tissue is a group of similar cells organized to perform a common function, and an organ is made of tissues working together. So the definition that identifies a cell as the smallest unit capable of performing life functions best captures what a cell is.

A cell is the basic unit of life—the smallest entity that can carry out the processes essential for life. It can perform metabolism, respond to its environment, grow, and, in many cases, reproduce. In single-celled organisms, one cell does all the life functions. In multicellular organisms, cells specialize and work together, but each cell still carries out its own life processes. A molecule is just a chemical unit of matter and isn’t alive by itself. A tissue is a group of similar cells organized to perform a common function, and an organ is made of tissues working together. So the definition that identifies a cell as the smallest unit capable of performing life functions best captures what a cell is.